Trots att hon byter jobb vill hon behålla vänskapen med sina gamla kollegor.

Trots att means although, even though, or despite the fact that.

It introduces a clause that contrasts with what happens in the main clause:

• Trots att hon byter jobb, vill hon behålla vänskapen ...
• Even though she is changing jobs, she wants to keep the friendship ...

A useful thing to remember is:

• trots
  • noun phrase
    
    • trots regnet = despite the rain
• trots att
  • clause
    
    • trots att det regnar = even though it is raining

So here, because a whole clause follows, Swedish uses trots att.

This is because Swedish main clauses follow the V2 rule: the finite verb usually comes in the second position.

The sentence starts with the subordinate clause:

• Trots att hon byter jobb

That whole clause takes the first position. So in the main clause, the finite verb must come next:

• vill hon behålla ...

That is why you get:

• Trots att hon byter jobb vill hon ...

and not:

• Trots att hon byter jobb hon vill ...

This is very common in Swedish when a sentence begins with a time clause, reason clause, condition clause, contrast clause, etc.

Because trots att introduces a subordinate clause, and subordinate clauses do not use the normal main-clause inversion pattern.

So you get normal subject + verb order:

• hon byter jobb

not:

• byter hon jobb

Compare:

• Main clause: Hon byter jobb.
• Subordinate clause: ... att hon byter jobb

This is a very important difference in Swedish:

• main clause: often V2
• subordinate clause: subject usually comes before the finite verb

In Swedish, some activities and roles are often expressed without an article, especially in common expressions.

Byta jobb is a standard expression meaning:

• change jobs
• switch jobs
• change one’s job

So Swedish normally says:

• byta jobb
• not usually byta ett jobb

Using an article would sound odd here unless you meant a very specific job in a special context.

This is similar to other article-free expressions in Swedish, such as:

• gå i skolan = go to school
• spela piano = play the piano / play piano
• ha bil = have a car

It can cover more than one of those ideas depending on context.

Swedish present tense is often broader than English present tense. Byter jobb can mean:

• she changes jobs
• she is changing jobs
• she is about to change jobs / is switching jobs

In this sentence, the natural English interpretation is usually:

• even though she is changing jobs

So yes, Swedish present tense often does work that English might express with a progressive form.

Because it comes after vill, which is a modal verb.

After modal verbs in Swedish, the next verb is normally in the infinitive without att:

• hon vill behålla
• she wants to keep

Other common examples:

• kan komma = can come
• ska läsa = will/is going to read
• måste gå = must go
• vill stanna = wants to stay

So:

• vill behålla is correct
• vill behåller is not correct

Vänskapen is the definite form: the friendship.

Swedish often uses the definite form when the noun is made specific by context or by a following phrase. Here, the friendship is specified by:

• med sina gamla kollegor

So it is not just friendship in general, but the specific friendship she has with those colleagues.

Also, using the singular here suggests the relationship as a whole:

• vänskapen med sina gamla kollegor = the friendship/bond with her old colleagues

If you said vänskap instead, it would sound more general or abstract.

Because sina is a reflexive possessive. It refers back to the subject of the clause, which is hon.

So:

• hon ... sina gamla kollegor = her own old colleagues

This is different from hennes, which normally refers to someone else’s possession, or is used when the possessor is not the subject of that clause.

Compare:

• Hon saknar sina kollegor.
  = She misses her own colleagues.
• Hon saknar hennes kollegor.
  = She misses her colleagues, meaning another woman’s colleagues.

In your sentence, the colleagues belong to the subject hon, so sina is the right choice.

Not necessarily. In this context, gamla kollegor usually means:

• former colleagues
• old colleagues in the sense of previous colleagues

It does not usually mean they are elderly.

Swedish gammal/gamla often works like English old, which can also mean former depending on context:

• min gamla lärare = my old/former teacher
• mitt gamla jobb = my old/former job

So here, the natural meaning is previous colleagues from her old workplace.

Because when Swedish uses a possessive such as min, din, hans, hennes, sin/sina, the noun phrase is already determined, so you do not also add the definite article ending.

That is why Swedish says:

• mina vänner
• hennes barn
• sina gamla kollegor

not:

• mina vännerna
• hennes barnen
• sina gamla kollegorna

So sina already does the job of making the noun phrase definite/identified.

Because it agrees with the noun phrase sina gamla kollegor.

A few things are happening:

• kollegor is plural
• sina is a possessive determiner
• after possessives, adjectives usually take the -a form

So:

• gammal = old (common singular indefinite)
• gamla = old (plural, and also the usual form after possessives/definite contexts)

That is why you get:

• sina gamla kollegor

and not:

• sina gammal kollegor

It goes with vänskapen:

• vänskapen med sina gamla kollegor

So the structure is:

• vill = wants
• behålla = keep/maintain
• vänskapen = the friendship
• med sina gamla kollegor = with her old colleagues

In other words, she wants to keep the friendship with her old colleagues.

This med phrase tells you who the friendship is with.

Sometimes, but jobb is much more natural here.

• byta jobb is the standard everyday expression for change jobs
• byta arbete is possible in some contexts, but sounds more formal or less idiomatic in ordinary speech

So for a normal modern sentence like this, byter jobb is exactly what most learners should aim for.